jmreiser

You might try the Durametric software & cable... www.durametric.com

Bad caps & rotors are common. It would run better with new ones, but billowing smoke is likely something else. Borrowing a MAF for a test is a great idea.

It could possibly be a bad oxy sensor... your car has just one, correct?

But rather than changing parts, we'd rather have the fault codes so we can get a better idea of what is going on in that poor ECU.

Peter R.

I am by now convinced the smoke (white a snow) is indeed raw fuel-air mixture that is exited from the ports unburnt. It consquently starts to evaporate in the hot exhaust, causing the occasional 'bang' from the pipe, and generally making big clouds and stinking of gasoline.

I hope the P-dealer has the parts on stock, and I will fit them tonight. I'll keep you posted.

If that doesn't do the trick, I'll buy a diagnostic too. If it does, I'll buy the tool anyway.

Peter R.

jmreiser

Which parts are you going to try? MAF, oxy sensor or both? MAF first?

Peter R.

Yeah, probably. The thing is I can't find anyone to part with the MAF.

I could just get the two, and bugger it. But let's see how the dizzy's pan out. The P-dealer was a rotor short this morning, but he'll have it delivered this afternoon so I can try the stuff tonight. Incidentally, I tried to pull off a rotot and it seemed like someone had glued it on. Hope I don't rip the dizzy shaft right out.

Peter R.

jmreiser

It seems extremely unlikely that the caps & rotors could explain this, unless one of the caps is totally cracked in half. Yes the rotors can get stuck if they are old, no question.

Peter R.

There's holes burnt in where the copper used to be. Copper's gone completely, just holes (up to 1 mm in diameter) left. Looks like a small version of the moon in there. And black soot everywhere. It's not pretty.

Peter R.

Peter R.

Funny thing...smoked as usual, pulled the plug on the MAF, a short hump in the running of the engine, but no difference whatsoever.

I'll order a MAF from pelican, they're cheap there.

Peter

StevoUK

Be careful - dont mess up the catalyst by running that gas cloud through it to often.

jmreiser

In the ignition caps?? Wow! Any chance of photos of this after you have your car working?

Red rooster

Euro 993 OBDI runs at idle OK with the MAF disconnected !
The DME uses the throttle position potentiometer as a substitute signal.

Geoff

Peter R.

This is way cool info. I'll start her up without the MAF tonight and will soon know if it's the MAF that's gone off.

Peter R.

Garth S

The dist. caps are far worse than the thought that prompted my first post - such severe erosion of the contacts as reported almost suggests that the engine is trying to fire 'out of time' ... ie., triggered to fire when the rotor is too far away from the cap contact .... which causes a too large gap ... which arcs the contacts to death.
The crankshaft position sensor is the reference for the DME trigger ... no?

jmreiser

Maybe the question is, did this condition start right after some service work, or all at once by itself, or slowly got worse over time?

Peter R.

It started after 6-7 weeks being parked outside in crappy weather because I was parked in a daft wheelchair, by which time the battery had died !

I've never heard of a crankshaft position sensor being off. Being broken, yes. The ECU has no idea where the crankshaft is so it simply won't start.

Peter R.

jmreiser

What happened next? Did you quick-start the car from another battery or a big charger? I wonder if something got damaged in the electronics...?

I had a crank position sensor go bad on me, on another vehicle, not a Porsche. The symptom was, first the car would stall out once or twice at low speed, then one morning a few weeks later, I drove it somewhere for breakfast, and when I was done, it wouldn't start. It sort of started one last time as we put it on a flatbed tow truck. So I agree with your answer 100% on that.